Leading Energy and Power Companies Rely on Tumbleweed Secure Content Management Solutions

Chevron, IDA Corp., Hawaiian Electric Industries, Jacobs Engineering and the U.S. Department of Energy all benefit from Tumbleweed's solutions for secure Internet communications

REDWOOD CITY, CA - September 10, 2001 - Tumbleweed® Communications Corp. (Nasdaq:TMWD), a leading provider of secure content management solutions for enabling the business Internet, today announced that Chevron, IDA Corp. (power company for the state of Idaho), Hawaiian Electric Industries and the Department of Energy have all deployed Tumbleweed's secure mail solutions to enable and secure their business communications with customers and partners on the Internet.

Increasing numbers of leading worldwide energy and power, oil and gas, as well as engineering firms are moving their business processes online and managing their business communications with Tumbleweed's comprehensive solutions that enable them to protect sensitive business data on the Internet. With Tumbleweed products, these companies can set and implement policies for communicating with their partners, suppliers and customers over the Internet, including email and browser-based communications, by applying content control, encryption, access control, attachment management, virus scanning and digital signature policies that are administered centrally and enforced universally across their enterprise.

According to Charlie Smith, a Technical Director with ACS at the U.S. Department of Energy, "On any given day, the Department of Energy can be hit by 2,000 viruses on its email system. With an end-user base of 10,000, we needed a solution that would enable us to stop these viruses at our gateway and prevent them from entering our system. Tumbleweed's solution provides the Department of Energy with complete security and protection for our network."

"We use Tumbleweed to secure our email communication stream with our partners because we needed a comprehensive solution that was easy to install and invisible to our end-users," said Sterling Yee, Hawaiian Electric Industries. "Tumbleweed enables us to communicate in a safe, secure environment over the Internet without requiring anyone to employ encryption technology-it's seamless."

Tumbleweed offers a comprehensive suite of secure mail, web, archive and secure content management products. "From exploration companies, to engineering firms, refineries, and gas and electric companies, as well as the entities that regulate these companies, our solution provides a complete secure communications platform to enable them to conduct business safely with one another over the Internet," said Jeffrey C. Smith, Chairman and CEO, Tumbleweed Communications Corp. "Using Tumbleweed solutions, our customers are able to protect and safeguard their enterprise and end-users from harmful content, ensure the confidentiality of their corporate data, and reduce costs by moving paper-based business processes to the Web."

About Tumbleweed
Tumbleweed is a leading provider of solutions for managing secure communication and collaboration to enable the business Internet. Tumbleweed's robust policy-based framework empowers organizations to safely share and protect critical information, increase customer loyalty and privacy and dramatically reduce costs. Tumbleweed is trusted by 1,000 blue-chip customers including American Express, JP Morgan Chase & Co., Chevron, Datek Online, the European Union's Joint Research Council, US Food and Drug Administration, John Deere, Merrill Lynch, Nike, Northern Trust, NTT, Salomon Smith Barney, Travelers, United Parcel Service, and seven of the world's largest postal services. Tumbleweed Communications was founded in 1993 and is headquartered in Redwood City, CA with offices around the world.

Except for the historical information contained herein, the matters discussed in this press release may constitute forward-looking statements that involve risks and uncertainties that could cause actual results to differ materially from those projected, particularly with respect to the security features of Tumbleweed's products and the activities of any third party. In some cases, forward-looking statements can be identified by terminology such as "may," "will," "should," "potential," "continue," "expects," "anticipates," "intends," "plans," "believes," "estimates," and similar expressions. For further cautions about the risks of investing in Tumbleweed, we refer you to the documents Tumbleweed files from time to time with the Securities and Exchange Commission, particularly Tumbleweed's Form 10-K filed March 30, 2001 and Form 10-Q filed November 13, 2001. Tumbleweed assumes no obligation to update information contained in this press release.